Method and device for delivering fluid, and a heat transfer cartridge

ABSTRACT

A method and device for delivering a fluid, in which the fluid is fed from a fluid source of a fluid-delivery device and delivered through a discharge orifice assigned to the delivery device. Before the fluid is delivered through the discharge orifice, it is heated or cooled by flowing through a heat-transfer chamber, which contains a fluid-permeable structure having a large number of communicating cavities through which the fluid flows.

FIELD OF THE INVENTION

The invention generally concerns a method and device for delivering afluid such as a gas or a liquid.

BACKGROUND OF THE INVENTION

In many industrial applications, fluid materials (fluids) are deliveredwith the aid of fluid-delivery devices and deposited on or applied tosubstrates. The fluid materials may be, for example, adhesives, paints,or sealing materials, and the substrates may be personal care products,plastic sheets, furniture, machine parts, or the like. Depending on theapplication, the fluid materials may be delivered, for example, in theform of beads, strips, or films, or the material may possibly be sprayedwith the aid of a gas jet that affects the fluid. The fluid-deliverydevices are connected to a fluid source, for example, an adhesivereservoir, and the fluid is fed by a pump through so-called applicationvalves to a discharge orifice, which is, for example, circular orslot-shaped.

In some applications, it is advantageous to heat the fluid before it isdelivered. In spray processes, it may be advantageous to heat a gas thatacts on the fluid to be delivered. For this purpose, it is well knownthat the base of the delivery device can be electrically heated, so thatliquid or gas flowing through flow channels formed in the base is heatedby convective heat transfer at the inner wall bounding the flow channel.To heat a gas in a fluid-delivery device, it is well known to use a gasflow channel that follows a zig-zag pattern. The purpose of the zig-zagdesign is to lengthen the flow path available for heat transfer and inthis way improve the heat transfer. However, this has the disadvantagethat the designs needed to produce this type of flow path are veryinvolved and thus expensive.

The goal of the present invention is to develop a method and device ofthe type described above and a cartridge to improve heat transfer.

SUMMARY OF THE INVENTION

The invention achieves the goal with respect to a method of the typedescribed above in such a way that, before it is delivered through thedischarge orifice, the fluid is heated or cooled by flowing through aheat-transfer chamber. The heat-transfer chamber contains afluid-permeable structure or foraminous body with a large number ofcommunicating cavities or interconnected interstices, such that thefluid circulates through this structure.

Furthermore, the invention achieves the goal with respect to a device ofthe type described above by a heat-transfer chamber for heating orcooling the fluid, which contains a fluid-permeable structure with alarge number of communicating cavities.

The advantages of the invention include significantly improving the heattransfer for heating or, alternatively, cooling a liquid and/or a gasbefore it is delivered by the delivery device. More specifically, thisadvantage is achieved by the fluid-permeable structure of the inventionthrough which the fluid circulates. The fluid-permeable structure ispreferably a sintered material, especially a sintered metal, which isessentially rigid and has a large number of intercommunicating cavitiesthrough which the fluid can circulate. Due to the fluid-permeablestructure present in the flow channel of the heat-transfer chamber, theheat transfer is improved by virtue of the fact that the surface areabetween the structure and the fluid to be heated or possibly cooled,which is crucial to the transfer of heat, is greatly increased andmultiplied. The structure is heated and the heat can be transferred tothe fluid over the large surface area of the structure. Furthermore, theheat transfer is improved by the fact that the fluid is repeatedlydeflected as it flows through the structure. This produces a certainamount of turbulence which, in turn, results in improved heat transfer.

In accordance with the invention, the heat transfer involved with, forexample, the heating of a liquid or a gas, is thus significantlyimproved and, as a result, the device can be built relatively compactly.Especially in the case of the heating of compressed gas for deliverydevices for spraying liquids, such as hot-melt adhesives, the increasedflow resistance produced by the fluid-permeable structure, compared to afree-flow channel, is negligible. The use of sintered metal as thepreferred material has the advantages that it has a large internalheat-transfer surface, is dimensionally stable, is easily produced andprocessed, and thus can be adapted to specific applications.Alternatively, however, it is also possible, in accordance with theinvention, to use other open-pored, preferably essentially rigid,structures, such as fabrics, metal braids, or rigid, open-pored cellularplastics.

Advantageously, as the fluid flows through the heat-transfer chamber, itcan be heated or cooled and simultaneously filtered by thefluid-permeable structure, so that, in addition to being heated, a gasor liquid is also purified.

To introduce heat into or remove heat from the fluid, thefluid-permeable structure is preferably in contact with the innersurface of the heat-transfer chamber. In this way, efficient heattransfer occurs.

It is especially preferred for the fluid to be a liquid, especially afluid plastic, such as a hot-melt adhesive, and for it to be heated byflowing through the heat-transfer chamber. It is likewise preferred forthe fluid to be a gas, preferably air, and for it to be heated byflowing through the heat-transfer chamber, which is advantageous inspray applications.

The device of the invention is refined by a simple design modificationby forming the heat-transfer chamber as a section of the flow channel,into which the fluid-permeable structure is inserted. In this way, theheat-transfer can be improved in a flow channel formed in a housing orbase of the delivery device in a simple way by inserting afluid-permeable structure of the invention.

It is especially preferred for the fluid-permeable structure to bedesigned essentially as a cylindrical body, which is inserted in anessentially cylindrical bore. This allows simple production andinstallation as well as replacement of the fluid-permeable structure.

A further advantage is realized if the fluid-permeable structure is amechanically finished sintered metal part, preferably a turned sinteredmetal part. The heat transfer between the sintered metal part and theheat-transfer chamber is further improved by mechanical finishing, e.g.,turning, of a surface of the sintered metal part that is in contact withthe heat-transfer chamber. As a result of the turning, the outer poresare partially sealed, and a larger contact surface is produced, withoutadversely affecting the inner structure, through which the fluid flows.

Advantageously, the heat-transfer chamber is formed in a metal housing,and the housing contains heating elements for heating the housing.

It is especially preferred for the fluid-permeable structure to bedesigned as part of a cartridge that can be inserted in the device. Thecartridge is detachably mounted in the device, and the fluid flowsthrough it. This allows fast and easy replacement of the cartridge. Itis advantageous for the cartridge to have at least one heating element.

In accordance with an alternative embodiment, it is proposed that thedevice have a base, in which the one or more heat-transfer chambers areinstalled, and that one or more application modules are provided, whichare installed on the base and contain the discharge orifice fordelivering the fluid. If needed, several heat-transfer chambers can beconnected in series or in parallel. They are preferably installed inseparate housing sections, which can be attached to one another.

Additional advantageous modifications will become apparent upon furtherreview of the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described below on the basis of preferred embodimentsillustrated in the attached drawings.

FIG. 1 shows a fluid-delivery device of the invention in a side view.

FIG. 2 shows the device in FIG. 1 in a different side view.

FIG. 3 shows a partial section of the device in FIG. 1.

FIG. 4 shows an alternative embodiment of several heat-transfer chambersfor a device in accordance with FIG. 1.

FIG. 5 shows an alternative embodiment of a fluid-delivery device, inwhich the fluid can be heated in accordance with the invention.

FIG. 6 shows a perspective view of a cylindrical sintered metal part.

FIG. 7 shows a perspective view of a cartridge for the fluid-deliverydevice.

FIG. 8 shows a perspective view of an alternative embodiment of acartridge.

FIG. 9 shows another alternative embodiment of a cartridge.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The device shown in FIGS. 1-3, which is also known as an applicator heador fluid-delivery device, is used to deliver and apply liquids, such asadhesives, hot-melt adhesive, cold glue, sealants, or the like, tovarious substrates. The device 1 comprises a metal base 2 and fourdelivery or application modules 4, 6, 8, 10, each of which is screwedonto the base 2 and from which the fluid is delivered through at leastone discharge orifice 12. The application modules 4, 6, 8, 10 may alsobe supplied with compressed gas, which emerges in the region of thedischarge orifices 12 through compressed gas nozzles and acts on thefluid in such a way that the fluid is sprayed or swirled. The substrateto be coated is conveyed past the device 1 below the discharge orificesby conveyance devices that are not shown in the drawings, for example,in the direction indicated by arrow 14. The device 1 can be mounted onsupport structures by fastening screws 16 fastened to the base 2.

A hose connection socket 18 serves to connect the device 1 with a fluidsource, such as an adhesive reservoir for liquid adhesive (not shown).The adhesive is conveyed through a flow channel which is composed ofseveral sections and runs through the base 2 and into the applicationmodules 4, 6, 8, 10 as far as the discharge orifices 12. The adhesiveflow channel has a first bore 20, which is shown only schematically bythe broken line, a transverse distribution channel 22, oblique bores 24,which communicate with the transverse distribution channel 22 and leadto each of the modules 4, 6, 8, 10, and additional channels, which areformed inside the application modules 4, 6, 8, 10 and open into thedischarge orifice 12.

To allow selective starting or stopping of the flow of the adhesiveinside the device 1, each module 4, 6, 8, 10 contains a valve system(not shown in detail), which has a valve body that can be movedpneumatically from an open to a closed position and interacts with avalve seat. The valve system is operated by an electrically controllablesolenoid valve 26, control air lines 28 connected to the solenoid valve,and compressed gas channels formed in the base 2, which are onlyindicated by the broken lines 30, 32 and serve to introduce compressedgas into the application modules 4, 6, 8, 10.

An air connection socket 34 is installed on the base 2 to supply gas,e.g., in the present embodiment, compressed gas. The compressed gasflows through several compressed gas channels, which are described ingreater detail below and are used for spraying or swirling the fluiddelivered through the discharge orifice 12.

For heating the spraying gas, preferably air, several heat-transferchambers 36, 38, 40, 42, 44, 46 are formed inside the base 2. The gasflows through the heat-transfer chambers in the direction indicated bythe arrows. In the present embodiment, there are two series-connectedpreheating heat-transfer chambers 36, 38 and four additional,parallel-connected heat-transfer chambers 40, 42, 44, 46, each of whichis assigned to an application module 4, 6, 8, 10. Alternatively,however, depending on the specific application, there may be differentnumbers of series-connected or parallel-connected heat-transfer chambersor even only a single heat-transfer chamber. The heat-transfer chambers36, 38, 40, 42, 44, 46 are arranged parallel to one another in a planein the upper section of the base. As FIGS. 2 and 3 show, the base 2 iscomposed of several housing sections, which are fastened to one anotherby screw joints. Each housing section holds at least one heat-transferchamber and serves to mount one of the application modules 4, 6, 8, 10.

A fluid-permeable structure that contains a large number ofcommunicating cavities is provided in each heat-transfer chamber. In theembodiment shown here, the structure is formed by cylindrical sinteredmetal parts 48. The heat-transfer chambers with the fluid-permeablestructures arranged within them serve primarily to improve the heattransfer, i.e., in the present embodiment, to improve the heating, ofthe gas flowing through the fluid-permeable structure. The sinteredmetal parts are essentially rigid and may consist, for example, of abronze-copper alloy. Alternatively, however, the fluid-permeablestructure may also consist of metal fabric, metal braid, or anopen-pored, rigid cellular plastic material, through which gas or liquidcan flow.

The sintered metal parts 48 are cylindrical and are fitted to andinserted in cylindrical bores 50 formed in the base 2. The addition orremoval of heat is explained in detail below. Each bore 50 is formed asa through-hole in the base or, more precisely, its housing sections. Thesintered metal parts 48 can be inserted from the inlet ends 52, whichare readily distinguishable in FIG. 3, of the bores 50. Both the inletends 52 and the opposite ends 54 of the bores 50 are provided withinternal threading, and, in the operating state, in a way not shownhere, can be sealed gastight with screw-in plugs. The gas introducedthrough the intake socket 34 flows through the heat-transfer chamber 36,then through a transverse bore 56 into the heat-transfer chamber 38,then through a transverse bore 58 into the heat-transfer chamber 40, andfinally into the application module 4. The gas also continues to flowthrough the additional transverse bores 60, 62, 64 into thecorresponding heat-transfer chambers 42, 44, 46 and then into thecorresponding application modules 6, 8, 10. To exchange the sinteredmetal parts 48, the plugs screwed into the inlet ends 52 are removed,and the sintered metal parts are taken out, possibly with the use oftools, which can be inserted through the opposite ends 54 to push outthe sintered metal parts 48.

To supply heat to the heat-transfer chambers 36-46 and thefluid-permeable structures (sintered metal parts 48), electricresistance heaters are installed inside the base 2, namely, insideseveral heater bores 58, 60, as FIG. 1 shows. In a way not shown in thedrawings, electric resistance heaters in cylindrical form are insertedin the bores 58, 60 and are supplied by electric current throughconnections 62 to the bores 58, 60. The resistance heaters constituteheating elements for heating the base 2. Thermal energy is transportedthrough the base 2 by thermal conduction, so that the individualheat-transfer chambers 36-46 and the fluid-permeable structures insertedin them can be heated to a sufficient temperature for thermal energy tobe transferred to the gas flowing through the fluid-permeable structure,and the gas is heated. Heat transfer is significantly improved by thefluid-permeable structure, since the surface area available for the heattransfer is significantly increased, and the gas circulating through thestructure is deflected and thus stirred up, which causes a certainamount of turbulence, which in turn promotes heat transfer. In a way notshown in the drawings, instead of heating elements, coolants could beprovided for cooling the base 2 and thus reducing the temperature of theheat-transfer chambers 36, 38, 40, 42, 44, 46 and the fluid-permeablestructure, for example, by introducing a coolant, such as a cooled gasor a liquid coolant, into the bores 58, 60.

FIG. 4 shows a sectional view of an alternative embodiment of a device1, which has a design that is basically similar to that of the device 1described with reference to FIGS. 1-3. The differences from the device 1described with reference to FIGS. 1-3 are explained below; otherwise,the above description applies completely to this alternative embodiment.The base 2 shown in FIG. 4 holds three application modules, which arenot shown in the drawing, to which three heat-transfer chambers 42, 44,46 are assigned and can be installed in the same way as shown in FIG. 3.Two heat-transfer chambers 36, 38 connected in series are formed in ahousing section 64 on the left side in FIG. 4. The fluid-permeablestructures in the form of sintered metal parts 50 are likewise insertedin cylindrical bores 48. Inlet ends 52 are provided for this purpose,which can be sealed by plugs, which are not shown in the drawing. Gas tobe heated is introduced through the intake 66. The gas can then flowthrough transverse bores 56, 58, 60 and 62 to the individualheat-transfer chambers 42, 44, 46 connected at the outlet ends of thetransverse bores.

FIG. 5 shows an alternative embodiment of a fluid-delivery device inaccordance with the invention, in which a liquid, such as hot-meltadhesive, is heated or cooled by a heat-transfer chamber 68 and afluid-permeable structure formed in it. As was explained in detailabove, the fluid-permeable structure is preferably designed as acylindrical sintered metal part 70, which is inserted in a cylindricalbore 72 formed in a base 2, so that there is contact between thesintered metal part 70 and the inner surface of the bore 72. As was alsoexplained earlier with reference to the first embodiment, thedescription of which completely applies here, the base 2 can be heatedby heating elements, preferably electric heating elements, or cooled bycoolants in a way not shown in FIG. 5, so that the adhesive flowingthrough the fluid-permeable structure is heated or cooled in theheat-transfer chamber 68 with the aid of the sintered metal part 70, asthe adhesive flows in the direction of arrow 74 from a fluid sourceconnected by a connection socket 18, through the heat-transfer chamber68 and through a bore 76 at the outlet of the heat-transfer chamber, toat least one application module 4, which has a discharge orifice 12 fordelivering the fluid.

FIG. 6 illustrates a fluid-permeable structure in accordance with theinvention in the form of a cylindrical sintered metal part, which can beinserted in a flow channel for a liquid or gas to be delivered by adelivery device 1 and is used for heat transfer, preferably for heating.The liquid or gas can be filtered at the same time. After it has beensintered, the sintered metal part 48 can be mechanically finished on itsouter cylindrical surface, preferably by turning, so that the poreslocated on the cylindrical surface are partially sealed by deformation,which results in the formation of an increased surface in contact withthe inner wall of a bore into which the sintered metal part 48 isinserted. The heat transfer is further improved in this way.Alternatively, in a way not shown in the drawing, it is also possible toplace several separate sections of sintered metal parts one afteranother in a row in a heat-transfer chamber.

FIG. 7 shows a cartridge 70 in accordance with the invention, which isintended to be inserted in a fluid-delivery device 1, for example, adevice of the type specified in the above descriptions. The cartridge 70can be detachably installed in a heat-transfer chamber 36, 38, 40, 42,44, 46, for example, with the use of plugs, bayonet sockets, screwfittings, or the like. The cartridge 70 has an external heating element72 in the form of a hollow cylinder. The heating element 72 is furnishedwith a large number of electrical conductors (not shown), which generateheat when an electric current flows through them. Electric connections(not shown) are provided for this purpose. The fluid-permeable structureof the invention in the form of a cylindrical body 74, preferably asintered metal part that fits into the cavity of the hollow cylinder, isformed inside the heating element 72. When the cartridge 70 is inserted,a liquid to be heated, for example, a hot melt adhesive, or a gas to beheated, for example compressed air, flows through the fluid-permeablestructure of the body 74 in the manner described earlier, so thatheating occurs.

The alternative embodiment of a cartridge 71 of the invention that isshown in FIG. 8 differs from the cartridge 70 described with referenceto FIG. 7 in that no heating element is provided; instead, a housing inthe form of a tube 73 is provided, which holds the fluid-permeablestructure, which is designed as a sintered metal part. The tube is made,for example, of aluminum or of another material that is a good heatconductor. Two grooves 76 are formed on the outer cylindrical surface ofthe tube 73 near the ends of the tube, into which gasket rings, forexample, O rings, can be inserted in a way not shown in the drawing toform a seal against a bore of the heat-transfer chamber in a base 2, sothat the fluid to be heated flows in a well-defined way through thefluid-permeable structure, which is designed as a sintered metal part74.

The alternative cartridge shown in FIG. 9 has a centrally installedelectric heating element 80 and a fluid-permeable structure in the formof a sintered metal part, which is designed as a hollow cylinder 82, inwhose inner cavity the heating element 80 is tightly fitted. Asexplained earlier, the cartridge 78 is likewise placed and detachablyfastened in a base of a fluid-delivery device 1, and fluid flows throughthe sintered metal part 80, so that it is heated.

In the example shown in FIG. 5, the hot-melt adhesive is heated in theheat-transfer chamber 68 and fed into the application module 4.

As illustrated in FIGS. 1-3, liquid flows through the connection socket18 into the base 2 and the modules 4, 6, 8, 10 and is then delivered bythe discharge orifice 12. Gas flows through the connection socket 34 andinto the base 2 and, in accordance with the invention, is heated byflowing through heat-transfer chambers 36, 38, 40, 42, 44, 46, possiblywith the use of cartridges of the type illustrated in FIGS. 6-9. To thisend, the inner wall of the heat-transfer chambers 36, 38, 40, 42, 44, 46and the fluid-permeable structure are heated by heating elements or, inthe case of cooling, cooled by coolants. The heated or cooled gas thencontinues to flow through the base 2 and into the application modules 4,6, 8, 10 and then, in its heated state, acts in such a way on the liquidto be delivered that atomization, turbulent swirling, or the likeoccurs.

1-33. Canceled.
 34. A method of transferring heat to or from a fluidflowing through a foraminous body positioned in a fluid chamber,comprising: feeding the fluid into the fluid chamber, heating or coolingthe foraminous body positioned in the fluid chamber, feeding the fluidthrough interstices of the foraminous body, transferring heat betweenthe fluid and the foraminous body, and delivering the fluid from theforaminous body to a fluid-delivery device.
 35. The method of claim 34,wherein feeding the fluid through the interstices of the foraminous bodyfurther comprises feeding the fluid through the interstices of asintered metal, a woven material, a metal fabric, or a cellular plastic.36. The method of claim 34, further comprising: filtering the fluid asthe fluid is fed through the interstices of the foraminous body.
 37. Themethod of claim 34, wherein the fluid is a liquid hot-melt adhesive. 38.A device for delivering a fluid, comprising: a dispensing body having aflow channel capable of being connected with a source of the fluid, anda discharge orifice communicating with said flow channel for deliveringthe fluid, a heat-transfer chamber communicating with said flow channel,a foraminous body positioned in said heat-transfer chamber and havinginterconnected interstices capable of receiving the fluid from said flowchannel and delivering the fluid to said discharge orifice, and a heattransfer device thermally coupled with said foraminous body and capableof transferring heat with respect thereto for heating or cooling thefluid flowing through the interconnected interstices.
 39. A device inaccordance with claim 38, wherein said foraminous body is constructedfrom a material selected from a group consisting of: a sinteredmaterial, a woven material, a metal braid, and an open-pored cellularplastic.
 40. A device in accordance with claim 38, wherein saidheat-transfer chamber is formed by a section of said flow channel intowhich said foraminous body is inserted.
 41. A device in accordance withclaim 38, further comprising: a housing containing said heat-transferchamber, said housing further containing heating elements for heatingthe foraminous body.
 42. A device in accordance with claim 38, furthercomprising: a cartridge carrying said foraminous body, said cartridgebeing insertable into and removable from said heat-transfer chamber. 43.A device in accordance with claim 42, further comprising: at least oneheating element carried by said cartridge.
 44. A device in accordancewith claim 43, wherein said foraminous body surrounds said heatingelement.
 45. A device in accordance with claim 43, wherein said heatingelement surrounds said foraminous body.
 46. A device in accordance withclaim 38, further comprising: at least one application valve modulecommunicating with said heat-transfer chamber and having said dischargeorifice for delivering the fluid.
 47. A cartridge for transferring heatto or from a fluid, comprising: a foraminous body having interconnectedinterstices through which the fluid may flow, and a heat transfer devicethermally coupled with said foraminous body and capable of transferringheat with respect thereto for heating or cooling the fluid flowingthrough the interconnected interstices.
 48. A cartridge in accordancewith claim 47, further comprising: a housing having a hollow interiorspace, said foraminous body positioned within said hollow interiorspace.
 49. A device in accordance with claim 47, wherein said foraminousbody is constructed from a material selected from a group consisting of:a sintered material, a woven material, a metal braid, and an open-poredcellular plastic.
 50. A device in accordance with claim 47, wherein saidforaminous body surrounds said heating element.
 51. A device inaccordance with claim 47, wherein said heating element surrounds saidforaminous body.